19544878091 has 2 divisors, whose sum is σ = 19544878092. Its totient is φ = 19544878090.

The previous prime is 19544878081. The next prime is 19544878163. The reversal of 19544878091 is 19087844591.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19544878091 is a prime.

It is not a weakly prime, because it can be changed into another prime (19544878051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9772439045 + 9772439046.

It is an arithmetic number, because the mean of its divisors is an integer number (9772439046).

Almost surely, 2^19544878091 is an apocalyptic number.

19544878091 is a deficient number, since it is larger than the sum of its proper divisors (1).

19544878091 is an equidigital number, since it uses as much as digits as its factorization.

19544878091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2903040, while the sum is 56.

The spelling of 19544878091 in words is "nineteen billion, five hundred forty-four million, eight hundred seventy-eight thousand, ninety-one".